1. Field of the Invention
An aspect of the present invention relates to a fuel tank check valve which is provided on a downstream of a fuel filler pipe of a fuel tank for a motor vehicle and the like.
2. Description of the Related Art
For example, a fuel filler pipe coupled to a fuel filler port is connected to a fuel tank for a motor vehicle, so that fuel is supplied into the fuel tank through the fuel filler pipe. Provided on a downstream (an outlet side) of the fuel filler pipe is a check valve which opens when fuel is supplied so as to permit flow of fuel into the fuel tank and closes when the fuel supply is completed so as to prevent reverse flow of fuel into the fuel filler pipe from the fuel tank.
There have been devised various constructions for mounting a check valve of this type on a fuel filler pipe. For example, Japanese Patent No. 3886344 discloses a fuel tank check valve including a main tubular body fitted on or in a fuel filler pipe and a valve element provided at a downstream portion of the main tubular body for permitting flow of fuel into the fuel tank and preventing flow of fuel out of the fuel tank, wherein a first tube having a first locking portion for the fuel filler pipe, an annular seal member adapted to be brought into abutment with a circumferential surface of the main tubular body and a circumferential surface of the fuel filler pipe and a second tube disposed further upstream than the first tube so as to hold the annular seal member between the first tube and itself and having a second locking portion for the main tubular body are disposed between the main tubular body and the fuel filler pipe, whereby the first locking portion of the first tube is brought into engagement with the fuel filler pipe for connection thereto upon the insertion of the fuel filler pipe. The first locking portion provided on the first tube is made up of an elastic locking arm which first projects radially inwards and then extends towards an upstream so as to hold the fuel filler pipe.
In Japanese Patent No. 3886344, the first locking portion of the first tube for the fuel filler pipe first projects radially inwards and then extends towards the upstream. When the first tube is coupled to the fuel filler pipe via the first locking portion, the first locking portion protrudes into an inside of the fuel filler pipe. As a result, a flowing resistance is increased, and fuel does not flow smoothly.